Male fertilization success depends on investment in both pre- and postcopulatory sexually selected traits, and considerable attention has recently been paid to quantifying the strength and direction of covariance between ...

Theoretical models predict that investment in pre-copulatory and post-copulatory sexually selected traits should trade-off. At the macroevolutionary scale, the majority of studies to date have focused on male weaponry as ...

Speciation research has largely overlooked reproductive barriers acting between copulation and the formation of the zygote (i.e., postmating, prezygotic [PMPZ] barriers), especially in internally fertilizing vertebrates. ...

Sperm exhibit extraordinary levels of morphological diversification across the animal kingdom. In songbirds, sperm have a helically shaped head incorporating a distinct acrosomal membrane or “helical keel,” the form and ...

Spermatozoa exhibit remarkable variability in size, shape, and performance. Our understanding of the molecular basis of this variation, however, is limited, especially in avian taxa. The zebra finch (Taeniopygia guttata) ...

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